Priming the Pump on a Dredge

In order to prime the centrifugal pump it will be necessary to move the end of the pump intake hose quickly up and down under the surface of the water. With each stroke the foot valve will release and will allow the water to flow into the pump intake hose. With each stroke the water in addition becomes trapped inside the hose when the butterfly valve closes. The water that has been trapped on the inside of the hose has a small amount of momentum and has a tendency of remaining there during the following stroke; this creates a small and low pressure area that increases the speed intake of the water while the butterfly valve opens. When this is moved up and down in this way the foot valve is like a small piston pump that forces the water up the intake hose in a very efficient way. To prime the centrifugal pump this has to push the water up around one or two feet and this does not have need of a lot of effort. After the priming water goes into the pump, the impellers push it outwards towards the pump housing very rapidly and this creates another low pressure area that pulls the water inside the intake hose to the impellers with a lot more momentum. This makes the foot valve remain open and water is constantly flowing to the impellers. While it may seem like a long explanation, in actuality the whole process only takes a few seconds, what is being described are the inner functions that occur. Something that a lot of people just starting out do by mistake is to not make the up and down thrusts quick enough so the momentum of the water in the intake tube can do what it needs to do. Move the foot valve quickly enough and the surge of water through the pump will happen so fast that you may be surprised.